Performance Analysis of Corroded Grounding Devices with an Accurate Corrosion Model

Grounding devices are significant to the operation of the power transmission line and power equipment. The soil and leakage current can easily cause the corrosion of carbon steel grounding devices, resulting in power accidents. Therefore, most carbon steel grounding devices in service are already corroded, and the accurate calculation of grounding parameters for corroded grounding devices is important. However, most existing methods for calculating the grounding parameters of corroded grounding devices usually have the following disadvantages: 1) They only consider whether the grounding devices are broken or not, and cannot analyze the grounding parameters of grounding devices with different corrosion degrees; 2) They assume that the corroded grounding device is a conductor with a smaller diameter, and ignore the impact of the corrosion product layer, resulting in calculation errors. To solve the above problems, this paper establishes an accurate corrosion model for grounding devices based on the volume expansion coefficient of corrosion products. The grounding parameters calculation method for corroded grounding devices is proposed based on the boundary element method (BEM) and Galerkin's method. Then the grounding performance of tower grounding grids with different corrosion degrees in different soils (uniform and layered) is analyzed. Finally, some features of grounding parameters of corroded grounding devices are given. This study can accurately calculate the grounding parameters of the corroded grounding devices and has far-reaching engineering significance for the safety of power equipment.